Recently, due to an environmental pollution resulting from an exhaust gas of vehicles, depletion of fossil fuel, and the like, electric vehicles or hybrid vehicles (referred to as ‘electric vehicles’, hereinafter) using an electric motor as a power source or an auxiliary power source are on the rise.
The electric motor may include an outer case, a stator disposed within the outer case, and a rotor disposed to be rotatable with respect to the stator.
Meanwhile, an electric motor used in an electronic vehicle is required to have a high output density, so the electric motor is required to have high cooling performance.
However, in the related art electric motor of an electric vehicle, a cooling unit is provided at the outer case, so a heat transmission path from a stator coil which generates heat to the cooling unit for cooling heat from the stator coil may be lengthened. Thus, there is a limitation in enhancing heat exchange efficiency and cooling performance by the cooling unit provided at the outer case.
Also, when the heat transmission path from the heat source to the cooling unit is lengthened, temperature of a heating component can be increased to result in a degradation of an output.
Also, a forcible degradation may be accelerated due to a temperature increase, and thus, a life span may be shortened.